Pharmacological and partial biochemical characterization of Bmaj-9 isolated from Bothrops marajoensis snake venom

bmaj-9, a basic pla2 (13679.33 da), was isolated from bothrops marajoensis snake venom through only one chromatographic step in reversed phase hplc on ？-bondapak c-18 column. the amino acid composition showed that bmaj-9 had a high content of lys, his, and arg, typical of a basic pla2. the sequence of bmaj-9 contains 124 amino acid residues with a pi value of 8.55, such as dlwqwgqmil ketgklpfsy ytaygcycgw ggrggkpkad tdrccfvhdc, revealing a high homology with asp49 pla2 from other snake venoms. it also exhibited a pronounced phospholipase a2 activity when compared with crude venom. in chick biventer cervicis preparations, the time for 50% and 100% neuromuscular paralysis was respectively (in minutes): 110 ± 10 (1 μg/ml); 40 ± 6 and 90 ± 2 (5 μg/ml); 30 ± 3 and 70 ± 5 (10 μg/ml); 42 ± 1 and 60 ± 2 (20 μg/ml), with no effect on the contractures elicited by either exogenous ach (110 μm) or kcl (20 mm). bmaj-9 (10 μg/ml) neither interfered with the muscular response to direct electrical stimulation in curarized preparations nor significantly altered the release of ck at 0, 15, 30 and 60 minutes incubations (27.4 ± 5, 74.2 ± 8, 161.0 ± 21 and 353.0 ± 47, respectively). the histological analysis showed that, even causing blockade at the maximum dosage (5 μg/ml), the toxin does not induce significant morphological alterations such as necrosis or infiltration of inflammatory cells. these results identified bmaj-9 as a new member of the basic asp49 pla2 family able to interact with the motor nerve terminal membrane, thereby inducing a presynaptic neuromuscular blockade.